78 K20 modernization project

[68 TT]

I am starting with a bare bones 71,000 mile 78 K20 Scottsdale camper special and plan on upgrading the creature comforts and the technology as well as fixing the body damage left over from the previous owner.

I already yanked the engine to do a mandatory clutch job so while I had the engine out I cleaned it up, installed a little bigger cam & lifters with matching valve springs and silicone valve stem seals, double roller timing set, all new gaskets, a Performer RPM intake, an Edelbrock 1406 carb and headers. When it went back in it got the new clutch and a rollerized pilot bushing along with the resurfaced flywheel.

Valve covers are an 85-86 vintage TPI Camaro part and come from the factory with studs and wide force spreader hold downs. They came stock a dull silver color so I painted them, the oil fill cap, breather and the air cleaner lid satin black so it all matched.

[68 TT]

Along the way during the clutch job I found the worst looking cap & rotor that I have ever seen on a running vehicle.

http://67-72chevytrucks.com/vboard/s...d.php?t=362601

Replaced those with an MSD cap & rotor kit and a spare stock coil I had on the shelf. Still need to find the new MSD plug wires I have in a box somewhere.

[68 TT]

The driver side all plastic window crank handle kept popping off the mounting stud so I decided to retrofit a set of late 60's & early 70's metal window crank handles.

http://67-72chevytrucks.com/vboard/s...d.php?t=359291

Not quite a bolt on deal but a quick hit of the die grinder fixed that.

They look like they belong on the truck.

[68 TT]

While I was doing the window crank handle job I decided I needed something better than the plain old cheap radio and single center dash speaker for tunes.

http://67-72chevytrucks.com/vboard/s...d.php?t=359332

I started with the door speaker install using some speakers I had on the shelf for another project.

[68 TT]

I installed an old post type cassette player from another car I had but it ended up having a dead digital display so I ended up cutting the dash to install a fully function modern CD player.

After that I built some cab corner speaker enclosures to house the 6x9's that matched the door speakers I robbed from another project.

http://67-72chevytrucks.com/vboard/s...d.php?t=359330

I still need to finish the edge filler pieces and seal the housings to the cab corners but it sounds great all ready so I have been putting it off for other more important projects.

[68 TT]

I ended up giving the Edelbrock 1406 carb back to my brother after he changed his mind about the trade I had made for it a while back so in order to keep the truck on the road I robbed the 750 Demon carburetor off my 68 Camaro that is not back on the road yet after a complete drivetrain rebuild and upgrade.

I had to cut a section out of the heat shield to clear the Demon fuel line but I haven't taken a pic of the Demon carb on there with the modified heat shield.

The stock Q-Jet worked fine on the stock engine but the air & fuel mixture screws did not make any changes when turned so it could not go back on the truck. The best I could get out of it was 6 inches of vacuum. With the 1406 I was able to get 14 inches of vacuum out of it. Not bad for the size of the cam in there. Isky 280 degree .480" lift hydraulic.

[Mr.Chevy4x4]

Nice truck. I really like the 3/4 ton 4x4's. What's that mounted on the back of the bed near the passenger tail light?

[68 TT]

Originally Posted by Mr.Chevy4x4

Nice truck. I really like the 3/4 ton 4x4's. What's that mounted on the back of the bed near the passenger tail light?

Thanks, those are low profile tie down points back by the tail lights.

[Driveway Dreams]

Nicely put together build. I have read most of those when you did them but I never read here. The most recent, is something I will be doing to mine too. Looks "right" in there. Good job.

[68 TT]

Originally Posted by Driveway Dreams

Nicely put together build. I have read most of those when you did them but I never read here. The most recent, is something I will be doing to mine too. Looks "right" in there. Good job.

Thanks, it is a slow process due to the complete lack of funds and no garage to work in but it is making some progress anyway.

The next part of that install is to see if I can get the newer wiper arms with the arm mounted spray nozzles to fit under the cowl and plumb them up for better washer performance. It will let me clean up the original owners mickey mouse washer hose routing job too.

When I do the auto trans conversion I will install the newer column I have that has control stalk delay wiper controls. Two speed wipers with no delay suck.

Don't know if I need to install the wiper motor from the delay wiper donor but I have that too if needed.

[STOCKISH]

Thats a really nice looking truck. Great job on it so far.

[68 TT]

Originally Posted by 1972SuperCheyenne

Thats a really nice looking truck. Great job on it so far.

Thanks. I can use all the motivation I can get to keep working on the truck.

Still a ton of stuff to do but I keep chipping away at the list.

[jawilder]

68_TT, you are giving me motivation to work on mine even more

I think I have your truck's year younger cousin! 79K20

[68 TT]

Originally Posted by jawilder

68_TT, you are giving me motivation to work on mine even more

I think I have your truck's year younger cousin! 79K20

A bed with the gas doors is like yours is on my shopping list at the wrecking yard.

I scored a perfect driver side door this weekend so I now have both front fenders and both sport mirror power doors to go on the truck some time soon. Just need to remove the wrecking yard makings and color match them to the truck before I put them on. I don't want to paint the whole thing yet until I get the bed I want on there.

[68 TT]

I scored big time this weekend courtesy of a C4C victim 87 K10 truck at the local pull it yourself wrecking yard.

I snagged both in-tank fuel pump / sending unit assemblies, the switching valve, all the wiring and fuel line plumbing as well as the 27-spline NP208 transfer case and the under dash ECM carrier. Saved me a ton of cash on the fuel system alone.

While I was there I also picked up a GM Goodwrench remanufactured 4L60E out of a 93 4x4 with the Vortec V6 so it also had the GM rated 2025 rpm stall converter in it which was also new with the reman trans. It has the early four-bolt tail housing so it bolted right to the NP208 without need for an adapter plate. New these were $1400 for the trans and ~$200 for the converter so nice score for $55. Don't know how old they are but the fluid was red and the pan was clean. I will have to check the converter to see if there is a manufacture date on it. I have used this torque converter in several other projects and it works great. With a strong small block it will stall to about 2200 to 2400 rpm which will be great for the cam that is in my 350.

I also grabbed the engine wire harness out of a red-blue connector PCM 93 C1500 so it will plug right into the 16197427 PCM I have for the project.

Out the door I spent less than $200 on everything.

My EFI and overdrive trans retrofit project are now much closer to happening. Now all that is left is to fabricate the Holley pattern to TBI adapter plate for my Performer RPM intake and get to work putting it all in the truck.

Once it is all in there I will have to figure out what to do with the driveshafts if I don't find a long bed 700-R4 / NP208 driveshaft donor before then. I would like to put completely different driveshafts in the 78 with the swap so I can keep the SM465 / NP205 setup complete as a package that can go back in easily or be sold as a package to somebody else who wants to go to a manual trans from an auto.

I have a nice one-piece aluminum driveshaft out of a C1500 that may go in there in place of the steel two-piece unit in the 78 now. I will have to take some measurements to see if it will work now that I have the new trans and transfer case. I'm pretty sure it will need to be shortened. No big deal.

[silvereagle07]

Nice progress! Your truck is looking good. The bumpers look great.

[89muscletruck]

Nice truck and really cool build man!

[Driveway Dreams]

Wow, someone from the salvage yard better call the cops up there and let them know they got robbed. Nice job on the parts!

[68 TT]

Originally Posted by Driveway Dreams

Wow, someone from the salvage yard better call the cops up there and let them know they got robbed. Nice job on the parts!

They have fixed prices for parts so every transmission is $55 no matter what it is and it comes with the converter.

All sending units are $9 no matter how rare they are but you have to buy the pumps separate.

The engine wire harness only cost $9 but took several hours to get out in one piece.

T-case with adapter housing was only $65 too.

An engine assembly with all the accessories is only $135.

I love that place.

[leegrady]

Fine looking truck!!! Nice to see someone doing it right. Great pics of the distributor cap by the way. I'd say she was running a little bit hot that night.


Bone stock red on red '81 GMC K2500 longbed 350/sm465/corp 14bolt outback and dana 60 upfrt.

[68 TT]

I had been mulling over my plans to change the 78 K20 to an overdrive automatic, installing a newer motor, converting it to EFI and upgrading it to power windows & locks and adding sport mirrors to it.

The truck has been so reliable and solid I had second thoughts about tearing it apart. I found a 74 K10 on CL for a reasonable amount of money that was missing the drive train.

I picked it up on Thursday and it came with an extra front clip and another set of axles & tires attached to the Blazer they were on because the kid didn't feel like taking them off of it to give me what was in the ad.

The 74 is a bare cab with nothing under the dash but it had factory A/C so it will be much easier to install than putting A/C into my heater only 78 K20. It also has the auto trans 4x4 tunnel so I won't have to fill that hole where the shifter goes through on the K20 and it has a sliding rear window the K20 also does not have.

The Blazer floors are really rusty and it has had some metal fatigue issues in the door jambs so I am just going to part it out and put the best stuff from the two onto the 74 K10 and scrap the rest of it. I thought about making it an off road beater with all the serviceable parts that come off of the other two trucks but don't feel like spending the money to make it safe to drive or put a drive train into it.

One of the clips that came with the new acquisition is a near perfect 70's vintage set that is painted exactly like my 78 K20 so that will be going onto the 78 to fix the damaged driver side fender and cancer infected passenger side fender. I may take the driver side door off of the Blazer to put onto the K20 if my attempt to straighten out the damaged edge on the current one doesn't turn out.

Pics of the clip swap on the 78 K20 to follow after I get the K10 and K5 merged into one and the carnage cleaned up.

[73chevyman]

i wish i was closer i'm in need of a cab lol my 73 is rotting like no tomorrow... po did some stuff to it that mother nature loved

[68 TT]

The clutch fork broke so I ended up yanking the whole drive train, resealing the leaky transfer case and the transmission adapter, and upgrading the engine to a high volume pump and installing new rod & main bearings.

http://67-72chevytrucks.com/vboard/s...t=clutch+broke

[68 TT]

The day after I got the whole drive train back into the truck, got it assembled and back onto the road the ignition mechanism failed.

http://67-72chevytrucks.com/vboard/s...=1#post4004633

It seemed quite coincidental to have something break right after I did all that work but nothing I did was even close to the failed part so it was purely bad luck. At least it failed in the morning when I was going it warm it up prior to heading off to work instead of failing at work and stranding me with a broke truck and no tools or parts to fix it with.

It is now back on the road and runs & drives better than it has since I owned it. It shifts smoothly into all gears with little to no effort and the clutch works with minimal pedal movement instead of having to push the pedal to the floor all the way to be able to shift as before. It is much nicer to drive now but the clutch still kills my knee to use it.

Now I can get back on the 67 C-10 to K10 conversion project after a couple week delay fixing the K20.

[68 TT]

Scored a great retrofit shifter boot for the NP205 shifter out of a wrecked Saturn with a manual trans that fits the NP205 boot retainer ring perfectly.

http://67-72chevytrucks.com/vboard/s...77#post4209677

Looks great, won't let in any noise, fumes or moisture like the damaged old one did.

Plenty of height for full range of motion with no binding.

The price was right too at only $3.